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  1. Fulltext Natural bioactive compounds targeting DNA methyltransferase enzymes in cancer: Mechanisms insights and efficiencies
    Aanniz T, Bouyahya A, Balahbib A, El Kadri K, Khalid A, Makeen HA, et al.
    Chem Biol Interact, 2024 Apr 01;392:110907.
    PMID: 38395253 DOI: 10.1016/j.cbi.2024.110907
    The regulation of gene expression is fundamental to health and life and is essentially carried out at the promoter region of the DNA of each gene. Depending on the molecular context, this region may be accessible or non-accessible (possibility of integration of RNA polymerase or not at this region). Among enzymes that control this process, DNA methyltransferase enzymes (DNMTs), are responsible for DNA demethylation at the CpG islands, particularly at the promoter regions, to regulate transcription. The aberrant activity of these enzymes, i.e. their abnormal expression or activity, can result in the repression or overactivation of gene expression. Consequently, this can generate cellular dysregulation leading to instability and tumor development. Several reports highlighted the involvement of DNMTs in human cancers. The inhibition or activation of DNMTs is a promising therapeutic approach in many human cancers. In the present work, we provide a comprehensive and critical summary of natural bioactive molecules as primary inhibitors of DNMTs in human cancers. The active compounds hold the potential to be developed as anti-cancer epidrugs targeting DNMTs.
  2. Fulltext Polymorphism of HLA and Susceptibility of Breast Cancer
    Aboulaghras S, Khalid A, Makeen HA, Alhazmi HA, Albratty M, Mohan S, et al.
    Front Biosci (Landmark Ed), 2024 Feb 05;29(2):55.
    PMID: 38420797 DOI: 10.31083/j.fbl2902055
    Breast cancer (BC) is the second most common malignancy in the world. Numerous studies have demonstrated the association between human leukocyte antigen (HLA) and cancer. The occurrence and development of BC are closely linked to genetic factors. Human leukocyte antigens G and E (HLA-G and HLA-E) are non-classical major histocompatibility complex (MHC) class I molecules. These molecules play an important role in immune surveillance by inhibiting the cytotoxic and natural killer T cells responsible for immune escape. The expression of HLA-G and HLA-E has been associated with several diseases, including tumors. The HLA system plays a key role in the escape of tumor cells from immune surveillance. This review aims to determine the correlation between BC susceptibility and HLA markers specific HLA alleles such as HLA-B07, HLA-DRB111, HLA-DRB113, and HLA-DRB115 are associated with an increased risk of developing BC. Furthermore, HLA-G mutations have been attributed to an elevated likelihood of metastasis in BC patients. Understanding the complex associations between the HLA system and BC development is critical for developing novel cancer prevention, detection, and treatment strategies. This review emphasizes the importance of analyzing HLA polymorphisms in the management of BC patients, as well as the urgent need for further research in this area.
  3. Fulltext The effects of phosphanegold(I) thiolates on the biological properties of Acanthamoeba castellanii belonging to the T4 genotype
    Siddiqui R, Abjani F, Yeo CI, Tiekink ER, Khan NA
    J Negat Results Biomed, 2017 Apr 03;16(1):6.
    PMID: 28366172 DOI: 10.1186/s12952-017-0070-7
    BACKGROUND: Gold compounds have shown promise in the treatment of non-communicable diseases such as rheumatoid arthritis and cancer, and are considered of value as anti-microbial agents against Gram-negative and Gram-positive bacteria, and have anti-parasitic properties against Schistosoma mansoni, Trypanosoma brucei, Plasmodium falciparum, Leishmania infantinum, Giardia lamblia, and Entamoeba histolytica. They are known to affect enzymatic activities that are required for the cellular respiration processes.

    METHODS: Anti-amoebic effects of phosphanegold(I) thiolates were tested against clinical isolate of A. castellanii belonging to the T4 genotype by employing viability assays, growth inhibition assays, encystation assays, excystation assays, and zymographic assays.

    RESULTS: The treatment of A. castellanii with the phosphanegold(I) thiolates tested (i) had no effect on the viability of A. castellanii as determined by Trypan blue exclusion test, (ii) did not affect amoebae growth using PYG growth medium, (iii) did not inhibit cellular differentiation, and (iv) had no effect on the extracellular proteolytic activities of A. castellanii.

    CONCLUSION: Being free-living amoeba, A. castellanii is a versatile respirator and possesses respiratory mechanisms that adapt to various aerobic and anaerobic environments to avoid toxic threats and adverse conditions. For the first time, our findings showed that A. castellanii exhibits resistance to the toxic effects of gold compounds and could prove to be an attractive model to study mechanisms of metal resistance in eukaryotic cells.

  4. Investigation of putative arene-C-H···π(quasi-chelate ring) interactions in copper(I) crystal structures
    Yeo CI, Halim SN, Ng SW, Tan SL, Zukerman-Schpector J, Ferreira MA, et al.
    Chem Commun (Camb), 2014 Jun 7;50(45):5984-6.
    PMID: 24763907 DOI: 10.1039/c4cc02040e
    Evidence for C-H···π(CuCl···HNCS) interactions, i.e. C-H···π(quasi-chelate ring) where a six-membered quasi-chelate ring is closed by an N-H···Cl hydrogen bond, is presented based on crystal structure analyses of (Ph3P)2Cu[ROC(=S)N(H)Ph]Cl. Similar intramolecular interactions are identified in related literature structures. Calculations suggest that the energy of attraction provided by such interactions approximates 3.5 kcal mol(-1).
  5. Fulltext 1,3-Bis(2-chloro-phen-yl)thio-urea: a monoclinic polymorph
    Yeo CI, Tiekink ER
    Acta Crystallogr Sect E Struct Rep Online, 2011 Nov;67(Pt 11):o2965.
    PMID: 22219989 DOI: 10.1107/S1600536811041894
    The title compound, C(13)H(10)Cl(2)N(2)S, represents a monoclinic polymorph of the previously reported ortho-rhom-bic form [Ramnathan et al. (1996 ▶). Acta Cryst. C52, 134-136]. The mol-ecule is twisted with the dihedral angle between the benzene rings being 55.37 (7)°. The N-H atoms are syn to each other, which contrasts their anti disposition in the ortho-rhom-bic form. In the crystal, mol-ecules assemble into zigzag chains along the c axis via N-H⋯S hydrogen bonds. Chains are connected into layers via C-H⋯Cl inter-actions, and these stack along the a axis.
  6. The influence of R substituents in triphenylphosphinegold(I) carbonimidothioates, Ph3PAu[SC(OR)=NPh] (R=Me, Et and iPr), upon in vitro cytotoxicity against the HT-29 colon cancer cell line and upon apoptotic pathways
    Yeo CI, Ooi KK, Akim AM, Ang KP, Fairuz ZA, Halim SN, et al.
    J Inorg Biochem, 2013 Oct;127:24-38.
    PMID: 23850666 DOI: 10.1016/j.jinorgbio.2013.05.011
    The Ph3PAu[SC(OR)=NPh], R=Me (1), Et (2) and iPr (3), compounds are significantly cytotoxic to the HT-29 cancer cell line with 1 being the most active. Based on human apoptosis PCR-array analysis, caspase activities, DNA fragmentation, cell apoptotic assays, intracellular reactive oxygen species (ROS) measurements and human topoisomerase I inhibition, induction of apoptosis is demonstrated and both the extrinsic and intrinsic pathways of apoptosis have been shown to occur. Compound 1 activates the p73 gene, whereas each of 2 and 3 activates the p53 gene. An additional apoptotic mechanism is exhibited by 2, that is, via the JNK/MAP pathway.
  7. Phosphanegold(I) thiolates, Ph3PAu[SC(OR)=NC 6H 4Me-4] for R = Me, Et and iPr, induce apoptosis, cell cycle arrest and inhibit cell invasion of HT-29 colon cancer cells through modulation of the nuclear factor-κB activation pathway and ubiquitination
    Ooi KK, Yeo CI, Ang KP, Akim AM, Cheah YK, Halim SN, et al.
    J Biol Inorg Chem, 2015 Jul;20(5):855-73.
    PMID: 26003312 DOI: 10.1007/s00775-015-1271-5
    The phosphanegold(I) carbonimidothioates, Ph3PAu{SC(OR)=NC6H4Me-4} for R = Me (1), Et (2) and iPr (3), feature linear P-Au-S coordination geometries and exhibit potent in vitro cytotoxicity against HT-29 colon cancer cells in both monolayer and multi-cellular spheroid models (e.g., IC50 = 11.9 ± 0.4 and 20.3 ± 0.3 μM for 2, respectively). Both intrinsic and extrinsic pathways of apoptosis are demonstrated by human apoptosis PCR array analysis, caspase activities, DNA fragmentation and cell apoptotic assays. Compounds 1-3 induce an extrinsic pathway that leads to down-regulation of NFκB. Compound 2 also exhibits an extrinsic apoptotic pathway involving the activation of both p53 and p73, whereas 3 activates p53 only. Lys48- and Lys63-linked polyubiquitination are also promoted by 1-3. Each of cytotoxic Ph3PAu{SC(OR)=NC6H4Me-4}, for R = Me (1), Et (2) and iPr (3), induce an intrinsic apoptotic pathway as well as an extrinsic pathway leading to down-regulation of NFκB. Lys48- and Lys63-linked polyubiquitination are promoted by 1-3 and these are able to inhibit cell invasion and to suppress the activity of TrxR.
  8. Fulltext Crystal structures of 5-amino-N-phenyl-3H-1,2,4-di-thia-zol-3-iminium chloride and 5-amino-N-(4-chloro-phen-yl)-3H-1,2,4-di-thia-zol-3-iminium chloride monohydrate
    Yeo CI, Tan YS, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Oct 1;71(Pt 10):1159-64.
    PMID: 26594396 DOI: 10.1107/S2056989015016655
    The crystal and mol-ecular structures of the title salt, C8H8N3S2 (+)·Cl(-), (I), and salt hydrate, C8H7ClN3S2 (+)·Cl(-)·H2O, (II), are described. The heterocyclic ring in (I) is statistically planar and forms a dihedral angle of 9.05 (12)° with the pendant phenyl ring. The comparable angle in (II) is 15.60 (12)°, indicating a greater twist in this cation. An evaluation of the bond lengths in the H2N-C-N-C-N sequence of each cation indicates significant delocalization of π-electron density over these atoms. The common feature of the crystal packing in (I) and (II) is the formation of charge-assisted amino-N-H⋯Cl(-) hydrogen bonds, leading to helical chains in (I) and zigzag chains in (II). In (I), these are linked by chains mediated by charge-assisted iminium-N(+)-H⋯Cl(-) hydrogen bonds into a three-dimensional architecture. In (II), the chains are linked into a layer by charge-assisted water-O-H⋯Cl(-) and water-O-H⋯O(water) hydrogen bonds with charge-assisted iminium-N(+)-H⋯O(water) hydrogen bonds providing the connections between the layers to generate the three-dimensional packing. In (II), the chloride anion and water mol-ecules are resolved into two proximate sites with the major component being present with a site occupancy factor of 0.9327 (18).
  9. Fulltext Crystal structure of bis-[μ-bis-(di-phenyl-phosphanyl)methane-κ(2) P:P']digold(I) dichloride acetone monosolvate monohydrate
    Yeo CI, Tan YS, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Aug 1;71(Pt 8):937-40.
    PMID: 26396760 DOI: 10.1107/S2056989015013341
    In the title complex salt, [Au2{(C6H5)2PCH2P(C6H5)2}]Cl2·(CH3)2C=O·H2O, the dication forms an eight-membered {-PCPAu}2 ring with a transannular aurophilic inter-action [Au⋯Au = 2.9743 (2) Å]. The ring approximates a flattened boat conformation, with the two methyl-ene C atoms lying ca 0.58-0.59 Å above the least-squares plane defined by the Au2P4 atoms (r.m.s. deviation = 0.0849 Å). One Cl(-) anion functions as a weak bridge between the Au(I) atoms [Au⋯Cl = 2.9492 (13) and 2.9776 (12) Å]. The second Cl(-) anion forms two (water)O-H⋯Cl hydrogen bonds about a centre of inversion, forming a centrosymmetric eight-membered {⋯HOH⋯Cl}2 supra-molecular square. Globally, the dications and loosely associated Cl(-) anions assemble into layers lying parallel to the ac plane, being connected by C-H⋯Cl,π(phen-yl) inter-actions. The supra-molecular squares and solvent acetone mol-ecules are sandwiched in the inter-layer region, being connected to the layers on either side by C-H⋯Cl,O(acetone) inter-actions.
  10. Fulltext A new monoclinic polymorph of 1,1'-bis-(di-phenyl-thio-phosphor-yl)ferrocene
    Tan YS, Yeo CI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Aug 1;71(Pt 8):886-9.
    PMID: 26396747 DOI: 10.1107/S2056989015012682
    The title compound, [Fe(C17H14PS)2], is a second monoclinic polymorph (P21/c, with Z' = 1) of the previously reported monoclinic (C2/c, with Z' = 1/2) form [Fang et al. (1995 ▸). Polyhedron, 14, 2403-2409]. In the new form, the S atoms lie to the same side of the mol-ecule with the pseudo S-P⋯P-S torsion angle being -53.09 (3)°. By contrast to this almost syn disposition, in the C2/c polymorph, the Fe atom lies on a centre of inversion so that the S atoms are strictly anti, with a pseudo-S-P⋯P-S torsion angle of 180°. The significant difference in mol-ecular conformation between the two forms does not result in major perturbations in the P=S bond lengths nor in the distorted tetra-hedral geometries about the P atoms. The crystal packing of the new monoclinic polymorph features weak Cp-C-H⋯π(phen-yl) inter-actions consolidating linear supra-molecular chains along the a axis. These pack with no directional inter-actions between them.
  11. A non-solvated form of [(Z)-O-methyl-N-(2-methyl-phen-yl)-thio-carbamato-κS](tri-phenyl-phosphane-κP)gold(I): crystal structure and Hirshfeld surface analysis
    Yeo CI, Tan SL, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Oct 1;72(Pt 10):1446-1452.
    PMID: 27746938
    The title compound, [Au(C9H10NOS)(C18H15P)], features a near linear P-Au-S arrangement defined by phosphane P and thiol-ate S atoms with the minor distortion from the ideal [P-Au-S is 177.61 (2)°] being traced in part to the close intra-molecular approach of an O atom [Au⋯O = 3.040 (2) Å]. The packing features supra-molecular layers lying parallel to (011) sustained by a combination of C-H⋯π and π-π [inter-centroid distance = 3.8033 (17) Å] inter-actions. The mol-ecular structure and packing are compared with those determined for a previously reported hemi-methanol solvate [Kuan et al. (2008 ▸). CrystEngComm, 10, 548-564]. Relatively minor differences are noted in the conformations of the rings in the Au-containing mol-ecules. A Hirshfeld surface analysis confirms the similarity in the packing with the most notable differences relating to the formation of C-H⋯S contacts between the constituents of the solvate.
  12. A monoclinic polymorph of [(Z)-N-(3-chloro-phen-yl)-O-methyl-thio-carbamato-κS](tri-phenyl-phosphane-κP)gold(I): crystal structure and Hirshfeld surface analysis
    Yeo CI, Tan SL, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Aug 1;72(Pt 8):1068-73.
    PMID: 27536384 DOI: 10.1107/S2056989016010781
    The title compound, [Au(C8H7ClNOS)(C18H15P)], is a monoclinic (P21/n, Z' = 1; form β) polymorph of the previously reported triclinic form (P-1, Z' = 1; form α) [Tadbuppa & Tiekink (2010 ▸). Acta Cryst. E66, m664]. The mol-ecular structures of both forms feature an almost linear gold(I) coordination geometry [P-Au-S = 175.62 (5)° in the title polymorph], being coordinated by thiol-ate S and phosphane P atoms, a Z conformation about the C=N bond and an intra-molecular Au⋯O contact. The major conformational difference relates to the relative orientations of the residues about the Au-S bond: the P-Au-S-C torsion angles are -8.4 (7) and 106.2 (7)° in forms α and β, respectively. The mol-ecular packing of form β features centrosymmetric aggregates sustained by aryl-C-H⋯O inter-actions, which are connected into a three-dimensional network by aryl-C-H⋯π contacts. The Hirshfeld analysis of forms α and β shows many similarities with the notable exception of the influence of C-H⋯O inter-actions in form β.
  13. [N,N-Bis(2-hy-droxy-eth-yl)di-thio-carbamato-κ2S,S']bis-(tri-phenyl-phosphane-κP)copper(I) chloro-form monosolvate: crystal structure, Hirshfeld surface analysis and solution NMR measurements
    Tan SL, Yeo CI, Heard PJ, Akien GR, Halcovitch NR, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2016 Dec 01;72(Pt 12):1799-1805.
    PMID: 27980834
    The title compound, [Cu(C5H5NO2S2)(C18H15P)2]·CHCl3, features a tetra-hedrally coordinated CuI atom within a P2S2 donor set defined by two phosphane P atoms and by two S atoms derived from a symmetrically coordinating di-thio-carbamate ligand. Both intra- and inter-molecular hy-droxy-O-H⋯O(hydroxy) hydrogen bonding is observed: the former closes an eight-membered {⋯HOC2NC2O} ring, whereas the latter connects centrosymmetrically related mol-ecules into dimeric aggregates via eight-membered {⋯H-O⋯H-O}2 synthons. The complex mol-ecules are arranged to form channels along the c axis in which reside the chloro-form mol-ecules, being connected by Cl⋯π(arene) and short S⋯Cl [3.3488 (9) Å] inter-actions. The inter-molecular inter-actions have been investigated further by Hirshfeld surface analysis, which shows the conventional hydrogen bonding to be very localized with the main contributors to the surface, at nearly 60%, being H⋯H contacts. Solution NMR studies indicate that whilst the same basic mol-ecular structure is retained in solution, the tri-phenyl-phosphane ligands are highly labile, exchanging rapidly with free Ph3P at room temperature.
  14. Fulltext Crystal structure of 1-(4-methyl-phen-yl)-3-(propan-2-yl-idene-amino)-thio-urea
    Jotani MM, Yeo CI, Tiekink ER
    Acta Crystallogr E Crystallogr Commun, 2015 Oct 01;71(Pt 10):1236-41.
    PMID: 26594415 DOI: 10.1107/S2056989015017624
    In the title thio-semicarbazone, C11H15N3S, the p-tolyl-N-H and imino-N-H groups are anti and syn, respectively, to the central thione-S atom. This allows for the formation of an intra-molecular p-tolyl-N-H⋯N(imino) hydrogen bond. The mol-ecule is twisted with the dihedral angle between the p-tolyl ring and the non-hydrogen atoms of the N=CMe2 residue being 29.27 (8)°. The crystal packing features supra-molecular layers lying in the bc plane whereby centrosymmetric aggregates sustained by eight-membered thio-amide {⋯HNCS}2 synthons are linked by further N-H⋯S hydrogen bonds. Layers are connected via methyl-C-H⋯π inter-actions. The supra-molecular aggregation was further investigated by an analysis of the Hirshfeld surface and comparison made to related structures.
  15. G2/M cell cycle arrest on HT-29 cancer cells and toxicity assessment of triphenylphosphanegold(I) carbonimidothioates, Ph3PAu[SC(OR)=NPh], R=Me, Et, and iPr, during zebrafish development
    Ooi KK, Yeo CI, Mahandaran T, Ang KP, Akim AM, Cheah YK, et al.
    J Inorg Biochem, 2017 01;166:173-181.
    PMID: 27865929 DOI: 10.1016/j.jinorgbio.2016.11.008
    Phosphanegold(I) thiolates, Ph3PAu[SC(OR)=NPh], R=Me (1), Et (2) and iPr (3), were previously shown to be significantly cytotoxic toward HT-29 cancer cells and to induce cell death by both intrinsic and extrinsic apoptotic pathways whereby 1 activated the p73 gene, and each of 2 and 3 activated p53; 2 also caused apoptotic cell death via the c-Jun N-terminal kinase/mitogen-activated protein kinase pathway. Apoptosis pathways have been further evaluated by mitochondrial cytochrome c measurements and annexin V screening, confirming apoptotic pathways of cell death. Cell cycle analysis showed the majority of treated HT-29 cells were arrested at the G2/M checkpoint after 24h; results of both assays were confirmed by changes in populations of relevant genes (PCR array analysis). Cell invasion studies showed inhibition of metastasis through Matrigel™ matrix to 17-22% cf. untreated cells. LC50values were determined in zebrafish (8.36, 8.17, and 7.64μM for 1-3). Finally, the zebrafish tolerated doses of 1 and 2 up to 0.625μM, and 3 was tolerated at even higher doses of up to 1.25μM.
  16. In vitro anti-bacterial and time kill evaluation of binuclear tricyclohexylphosphanesilver(I) dithiocarbamates, {Cy3PAg(S2CNRR')}2
    Tan YJ, Tan YS, Yeo CI, Chew J, Tiekink ERT
    J Inorg Biochem, 2019 03;192:107-118.
    PMID: 30640150 DOI: 10.1016/j.jinorgbio.2018.12.017
    Four binuclear phosphanesilver(I) dithiocarbamates, {cyclohexyl3PAg(S2CNRR')}2 for R = R' = Et (1), CH2CH2 (2), CH2CH2OH (3) and R = Me, R' = CH2CH2OH (4) have been synthesised and characterised by spectroscopy and crystallography, and feature tri-connective, μ2-bridging dithiocarbamate ligands and distorted tetrahedral geometries based on PS3 donor sets. The compounds were evaluated for anti-bacterial activity against a total of 12 clinically important pathogens. Based on minimum inhibitory concentration (MIC) and cell viability tests (human embryonic kidney cells, HEK 293), 1-4 are specifically active against Gram-positive bacteria while demonstrating low toxicity; 3 and 4 are active against methicillin resistant S. aureus (MRSA). Across the series, 4 was most effective and was more active than the standard anti-biotic chloramphenicol. Time kill assays reveal 1-4 to exhibit both time- and concentration-dependent pharmacokinetics against susceptible bacteria. Compound 4 demonstrates rapid (within 2 h) bactericidal activity at 1 and 2 × MIC to reach a maximum decrease of 5.2 log10 CFU/mL against S. aureus (MRSA).
  17. Fulltext A triclinic polymorph of tri-cyclo-hexyl-phosphane sulfide: crystal structure and Hirshfeld surface analysis
    Tan YJ, Yeo CI, Halcovitch NR, Jotani MM, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 Apr 01;73(Pt 4):493-499.
    PMID: 28435705 DOI: 10.1107/S205698901700353X
    The title compound, (C6H11)3PS (systematic name: tri-cyclo-hexyl-λ(5)-phosphane-thione), is a triclinic (P-1, Z' = 1) polymorph of the previously reported ortho-rhom-bic form (Pnma, Z' = 1/2) [Kerr et al. (1977 ▸). Can. J. Chem. 55, 3081-3085; Reibenspies et al. (1996 ▸). Z. Kristallogr. 211, 400]. While conformational differences exist between the non-symmetric mol-ecule in the triclinic polymorph, cf. the mirror-symmetric mol-ecule in the ortho-rhom-bic form, these differences are not chemically significant. The major feature of the mol-ecular packing in the triclinic polymorph is the formation of linear chains along the a axis sustained by methine-C-H⋯S(thione) inter-actions. The chains pack with no directional inter-actions between them. The analysis of the Hirshfeld surface for both polymorphs indicates a high degree of similarity, being dominated by H⋯H (ca 90%) and S⋯H/H⋯S contacts.
  18. Fulltext Gold-Based Medicine: A Paradigm Shift in Anti-Cancer Therapy?
    Yeo CI, Ooi KK, Tiekink ERT
    Molecules, 2018 Jun 11;23(6).
    PMID: 29891764 DOI: 10.3390/molecules23061410
    A new era of metal-based drugs started in the 1960s, heralded by the discovery of potent platinum-based complexes, commencing with cisplatin [(H₃N)₂PtCl₂], which are effective anti-cancer chemotherapeutic drugs. While clinical applications of gold-based drugs largely relate to the treatment of rheumatoid arthritis, attention has turned to the investigation of the efficacy of gold(I) and gold(III) compounds for anti-cancer applications. This review article provides an account of the latest research conducted during the last decade or so on the development of gold compounds and their potential activities against several cancers as well as a summary of possible mechanisms of action/biological targets. The promising activities and increasing knowledge of gold-based drug metabolism ensures that continued efforts will be made to develop gold-based anti-cancer agents.
  19. Fulltext A new monoclinic polymorph of N-(3-methyl-phen-yl)eth-oxy-carbo-thio-amide: crystal structure and Hirshfeld surface analysis
    Jotani MM, Yeo CI, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 Dec 01;73(Pt 12):1889-1897.
    PMID: 29250410 DOI: 10.1107/S2056989017016280
    The title compound, C10H13NOS, is a second monoclinic polymorph (space group P21/c, Z' = 2) of the previously reported C2/c (Z = 1) polymorph [Tadbuppa & Tiekink (2005 ▸). Z. Kristallogr. New Cryst. Struct. 220, 395-396]. Two independent mol-ecules comprise the asymmetric unit of the new polymorph and each of these exists as a thioamide-thione tautomer. In each molecule, the central CNOS chromophore is strictly planar [r.m.s. deviations = 0.0003 and 0.0015 Å] and forms dihedral angles of 6.17 (5) and 20.78 (5)° with the N-bound 3-tolyl rings, thereby representing the major difference between the mol-ecules. The thione-S and thio-amide-N-H atoms are syn in each mol-ecule and this facilitates the formation of an eight-membered thio-amide {⋯SCNH}2 synthon between them; the dimeric aggregates are consolidated by pairwise 3-tolyl-C-H⋯S inter-actions. In the extended structure, supra-molecular layers parallel to (102) are formed via a combination of 3-tolyl-C-H⋯π(3-tol-yl) and weak π-π inter-actions [inter-centroid distance between 3-tolyl rings = 3.8535 (12) Å]. An analysis of the Hirshfeld surfaces calculated for both polymorphs reveals the near equivalence of one of the independent mol-ecules of the P21/c form to that in the C2/c form.
  20. Fulltext μ3-Chlorido-μ2-chlorido-(μ3-pyrrolidine-1-carbo-dithio-ato-κ4S:S,S':S')tris-[(tri-ethyl-phosphane-κP)copper(I)]: crystal structure and Hirshfeld surface analysis
    Tan YJ, Yeo CI, Halcovitch NR, Jotani MM, Tiekink ERT
    Acta Crystallogr E Crystallogr Commun, 2017 May 01;73(Pt 5):720-725.
    PMID: 28529784 DOI: 10.1107/S2056989017005382
    The title trinuclear compound, [Cu3(C5H8NS2)Cl2(C6H15P)3], has the di-thio-carbamate ligand symmetrically chelating one CuI atom and each of the S atoms bridging to another CuI atom. Both chloride ligands are bridging, one being μ3- and the other μ2-bridging. Each Et3P ligand occupies a terminal position. Two of the CuI atoms exist within Cl2PS donor sets and the third is based on a ClPS2 donor set, with each coordination geometry based on a distorted tetra-hedron. The constituents defining the core of the mol-ecule, i.e. Cu3Cl2S2, occupy seven corners of a distorted cube. In the crystal, linear supra-molecular chains along the c axis are formed via phosphane-methyl-ene-C-H⋯Cl and pyrrolidine-methyl-ene-C-H⋯π(chelate) inter-actions, and these chains pack without directional inter-actions between them. An analysis of the Hirshfeld surface points to the predominance of H atoms at the surface, i.e. contributing 86.6% to the surface, and also highlights the presence of C-H⋯π(chelate) inter-actions.
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